1. Field of the Invention
The present invention relates to redundant computer systems for computer servers and the like, and more particularly, to a system and method for interconnecting redundant systems.
2. Description of Related Art
Redundant systems are appropriate for various computing applications. As used herein, redundancy refers to duplication of electronic elements to provide alternative functional channels in case of failure, and a redundant node or element is one that provides this redundancy. A redundant system is a system containing redundant nodes or elements for primary system functions.
In a redundant computing system, two or more computers are utilized to perform a processing function in parallel. If one computer of the system fails, the other systems are capable of handling the processing function, so that the system as a whole can continue to operate. Redundant computing systems have been designed for many different applications, using many different architectures. In general, as computer capabilities and standards evolve and change, so do the optimal architectures for redundant systems.
For example, a standard may permit or require that the connectivity architecture for a redundant system be Ethernet-based. One such standard is the PCI Industrial Computer Manufacturers Group (PICMG) PSB Standard No. 2.16, about which more information may be obtained at www.picmg.com. In an Ethernet-based system, redundant nodes of the system communicate using an Ethernet protocol. Such systems may be particularly appropriate for redundant server applications. A redundant server comprises two or more separate computer servers (herein called “drawers”) connected by a suitable interconnect.
It is desired, therefore, to provide a redundant system suitable for use with an Ethernet-based connectivity architecture, and with other connectivity architectures. It is further desired to provide a system and method for interconnecting drawers of the redundant system. The system and method should support operation of the drawers in a redundant mode. That is, if one drawer of the system experiences a failure, the other drawer or drawers of the system should be able to assume the processing function that has been lost by the failure, via an interconnection. At the same time, the system and method should provide that if the interconnection fails (i.e., if there is a “connection failure”), it is immediately detected by each affected drawer. The connection failure may then be reported, and the affected drawers may operate in a non-redundant mode until the connection failure can be repaired.